A Case Against Cardio

Wow, what a great discussion. Seems to me we've got abit hung up on the definitions and values of different types of exercise. But some things are well researched.

In my days in medical research (left to become a winemaker in 2000) I remember teaching about the inverted J curve of exercise intensity duration and the immune system response. If you exercise or do some activity at 85% or more exertion/heart rate for more than 45 minutes per day you measureably compromise your immune system. Also after a bout of high intensity exercise there is a 'window' of approximately 2 hours when you immune system is measurably depleted or less active and you may be more susceptible to developing an infection, especially respiratory tract infection IF there are sufficient germs around, either loitering in your upper airways or arriving from other individuals.

As you drop back on the intensity this effect goes away and you can exercise all day long (just like Mark Sisson found). In ELITE athletes there is an observable increase in the incidence of upper repiratory tract infections, and in females, urinary tract infections immediately prior to, during and immediately after major competitions. There may also be an increase in skin infections though this was less clear. And there is an observable increase in injuries of the muscles and joints.

BUT - the other bit of the inverted J curve is very important. As you increase your exercise/activity levels your health by many measures improve in an almost direct fashion. This includes heart health, improved mobility of joints, mood, appetite regulation, insulin/sugar regulation and immune responsiveness.

What does this mean for us average folk who just want to get fit and have fun? Cardio is really good for you.
Don't overdo it, but do do it. Long bouts of sub-maximal exercise like walking, working, biking is really good and you can go all day if you want. Weight training has measurable benefits as listed above but don't over do it. Don't do the high intensity stuff for too long at a time. The fitness nuts who do long sessions of tabata and extreme spin are fit but not necessarily as healthy as they could be.

Just my 2 cents worth.

I just think it's a big mistake to take data from elite athletic performers and try to extrapolate that to the general population. Elite athletes DO NOT EXERCISE FOR HEALTH--they train to compete. The two do not always coincide. Part of "peaking" for athletic performance means taking your body as close to the edge as possible -- in Daniel Coyle's book about Lance Armstrong he writes that professional cyclists call it "going out on the razor". In preparation for something like the Tour de France, the top candidates for overall victory bring their body fat down to dangerous levels. As stated, their immune systems are compromised. They avoid physical contact, will only open doors and push elevator buttons with their elbows, get winded walking up a flight of stairs (in fact avoid walking altogether whenever possible). They focus on one thing only -- being able to ride a bike fast, 4-7 hours a day for 20 of the next 22 days.

You cannot take that data/experience and use it as a basis for denigrating cardio exercise in the general population. Not if you want any credibility, that is.

I don't know what the point of doing ANY sport at less than maximum effort, or for less than 30 minutes would be. Why would you just get started and then stop?

Wow, what a great discussion. Seems to me we've got abit hung up on the definitions and values of different types of exercise. But some things are well researched.

In my days in medical research (left to become a winemaker in 2000) I remember teaching about the inverted J curve of exercise intensity duration and the immune system response. If you exercise or do some activity at 85% or more exertion/heart rate for more than 45 minutes per day you measureably compromise your immune system. Also after a bout of high intensity exercise there is a 'window' of approximately 2 hours when you immune system is measurably depleted or less active and you may be more susceptible to developing an infection, especially respiratory tract infection IF there are sufficient germs around, either loitering in your upper airways or arriving from other individuals.

As you drop back on the intensity this effect goes away and you can exercise all day long (just like Mark Sisson found). In ELITE athletes there is an observable increase in the incidence of upper repiratory tract infections, and in females, urinary tract infections immediately prior to, during and immediately after major competitions. There may also be an increase in skin infections though this was less clear. And there is an observable increase in injuries of the muscles and joints.

BUT - the other bit of the inverted J curve is very important. As you increase your exercise/activity levels your health by many measures improve in an almost direct fashion. This includes heart health, improved mobility of joints, mood, appetite regulation, insulin/sugar regulation and immune responsiveness.

What does this mean for us average folk who just want to get fit and have fun? Cardio is really good for you.
Don't overdo it, but do do it. Long bouts of sub-maximal exercise like walking, working, biking is really good and you can go all day if you want. Weight training has measurable benefits as listed above but don't over do it. Don't do the high intensity stuff for too long at a time. The fitness nuts who do long sessions of tabata and extreme spin are fit but not necessarily as healthy as they could be.

Just my 2 cents worth.

I just think it's a big mistake to take data from elite athletic performers and try to extrapolate that to the general population. Elite athletes DO NOT EXERCISE FOR HEALTH--they train to compete. The two do not always coincide. Part of "peaking" for athletic performance means taking your body as close to the edge as possible -- in Daniel Coyle's book about Lance Armstrong he writes that professional cyclists call it "going out on the razor". In preparation for something like the Tour de France, the top candidates for overall victory bring their body fat down to dangerous levels. As stated, their immune systems are compromised. They avoid physical contact, will only open doors and push elevator buttons with their elbows, get winded walking up a flight of stairs (in fact avoid walking altogether whenever possible). They focus on one thing only -- being able to ride a bike fast, 4-7 hours a day for 20 of the next 22 days.

You cannot take that data/experience and use it as a basis for denigrating cardio exercise in the general population. Not if you want any credibility, that is.

Could you explain the phenomenon of "overtraining" and how that might fit into this discussion? (I don't know if overtraining is thought to involve compromised immunity, but I feel like I have heard that.) Is it simply a myth insofar as the "average joe" or even the non-elite athlete is concerned?

Overtraining is a condition that occurs when the volume and intensity of a workout program overwhelms the body's ability to recover. Overtraining is characterized by elevated resting heart rate, irritability, chronic fatigue, insomnia, yes, compromised immunity, and a dropoff in performance. You keep pushing but stop improving and actually start to regress. Overtraining can occur with anyone--it's not just something that athletes experience. There are no set guidelines as to how it occurs--by that I mean that you can't say: oh, at 5 days/wk you are fine, but 6 days/wk will cause problems. Some people are able to exercise daily, but build in "active rest", fuel replenishment, etc so that they stay underneath the "redline", but those who follow high volume, higher-intensity programs will usually bump up against it at some point. As long as you recognize it and are not obsessive, you just take a few days off, ease back into things and go on your way.

As far as weight loss goes, overtraining can lead to chronically elevated levels of stress hormones that might interfere with fat loss. I don't know that the two (overtraining and impaired fat loss) automatically go together, but they probably do.

http://www.bodyrecomposition.com/fat-loss/what-defines-cardio-in-terms-of-too-much-qa.html
http://www.bodyrecomposition.com/fat-loss/why-big-caloric-deficits-and-lots-of-activity-can-hurt-fat-loss.html